Before you go too far with your decision to train your Bully to stop barking, it is important that you realize this is his way of communicating with other dogs, you, your family, and the rest of the world. It is his way of alerting you to strangers, emergencies, other dogs that have wandered into the yard, and many other situations.
Of course, this doesn't mean your Pittie should bark incessantly, driving the neighbors crazy. It simply means you need to teach your pup when it's okay for him to bark and when he needs to be quiet.
The task itself is pretty simple, your job is to teach your pup to be quiet on command and at the same time, not to bark just because he feels like it. Again, keep in mind there are many valid reasons for your pup to bark, so you should not try to teach him to never bark. Pay close attention to when your pup is barking to see if he is making noise for a good reason or he just likes the sound of his own voice. Then you can work on training him to be quiet on command and eventually just because he knows that barking does not result in getting a reward.
Before you contemplate teaching your Bully not to bark, he needs to have mastered the four basic commands: 'sit', 'stay', 'come', and 'down'. This helps to establish you as the alpha in his pack, which in turn will make training him that much easier. Beyond a large bag of your pup's favorite treats, be prepared with plenty of time and patience to keep working with your pup.